HSBC bosses yesterday denied Britain's biggest bank had become unmanageable after admitting its complex structure and global spread had seen it targeted by criminal organisations.

Chief executive Stuart Gulliver told the parliamentary commission on banking standards that HSBC had been forced into the biggest restructuring since it was founded in 1865.

Gulliver and HSBC chairman Douglas Flint were giving evidence three months after the bank paid £1.2billion to settle a criminal investigation into its Mexican and US operations that saw it facing allegations it had "been a conduit for drug kingpins and rogue nations".

The probe found that lax controls had allowed two drug cartels to move $881million through the bank.

Our structure was not fit for purpose.

Gulliver said: "Our structure was not fit for purpose. Our geographic footprint became very attractive to trans-national criminal organisations.

We've crushed our reputation with the Mexico events."

After taking the helm two years ago, Gulliver centralised control and created global business operations, removing much of the control from country managers.

Some senior people have been removed from the bank for "value breaches".

Gulliver added: "I don't believe this bank is too big to manage. We have reorganised HSBC to the highest standards."